1. Field of the Invention
This invention relates generally to operational electric switches for wall- or ceiling mounted devices such as hazard detectors, and more particularly, to a repetitively useable on/off switch which is engaged or disengaged whenever the device/detector is installed or uninstalled, respectively.
2. Background Information
Many hazard detectors, such as fire, smoke, gas, heat, and proximity (motion) types are known and used in residential dwellings and commercial buildings. These are also termed ambient condition monitors or detectors and operate off internal and external power sources. The internal power sources are generally single or ganged batteries of practically every commercially available type, including those described generically as long-life. Although the present invention does not apply only to use of the long-life battery, its greatest utility is realized therewith, because modern production methods and economics have fostered the idea of transshipping detectors, and other battery-using devices, with the batteries installed. Indeed, in some instances, the device contains the battery power supply installed, and even hard-wired, into the operative circuitry; but, this feature can only be employed where care is taken to comply with current industrial safety and transportation laws that may not allow movement of xe2x80x9chotxe2x80x9d or xe2x80x9cactivexe2x80x9d electrical devices. Moreover, from the perspective of battery life, it is generally undesirable to have the device xe2x80x9chotxe2x80x9d or xe2x80x9cactivexe2x80x9d during shipment and while the device remains in a retailer""s inventory. It is to exploit this quiescent, yet battery-installed, feature that the instant invention is provided and prior art now discussed.
In U.S. Pat. No. 5,578,996, issued for a LONG LIFE DETECTOR, there is disclosed a seemingly conventional ambient condition, surface-mountable detector which contains within its construction: a mounting bracket; a base, which contains part of a single-use, frangible, and rotatable switch mechanism, the complementary switch portion, borne on a circuit board, which is attached also to the base and secures a hard-wired, long-life battery, and a protective cover. The detector remains inactive until its installation, which requires insertion of a flat- or chisel-blade screwdriver into a slot of the switch and rotation thereof to break a frangible restraint, thus closing the switch and activating the detector. Until activation, the frangible switch impedes mounting of the detector to its bracket; the bracket serving no other function than to secure the detector (proper) to a surface. Upon reaching the end of its useful life, the detector is removed from its bracket and a screwdriver is again used to rotate the aforesaid switch to a battery xe2x80x9cdrainxe2x80x9d position in which a second switch may be actuated to drain the battery. Thereafter the unit is discarded. This disclosure is silent regarding whether the switch is capable of retrograde motion that would allow the unit""s deactivation for removal, storage and later movement to alternate locations; in the (disclosed) alternate embodiments, retrograde motion is foreclosed.
In another disclosure, U.S. Pat. No. 5,793,295, providing a DETECTION APPARATUS AND METHOD, an operational switching mechanism for a gas sensor is shown that uses a key member to house a battery package, but does not entertain a circuit-inclusive battery feature. The key, when inserted, activates the circuit irrespective of the installation status of the sensor; thus giving rise to a severe impediment to satisfying the aforesaid quiescent, battery-installed feature that is desired by the instant inventor.
An EXTENDED LIFE SMOKE DETECTOR, as disclosed in U.S. Pat. No. 5,444,434, avoids use of a physical on/off switch. The avoidance of the switch, according to the purpose stated therein, is to preclude mishaps that can occur due to improper or negligent usage. The patentee""s objectives are met by constructing the device in an incipiently operative mode, providing extended long- life batteries (up to 12 years use) and avoiding the likelihood of accidental or negligent disablement, by withholding the switch/shutoff means. In the preferred embodiment, the batteries are factory-soldered into the circuitry and the external cover is permanently fixed to the (operative) detector.
Earlier hazard detectors were provided a switching that, although distinctive from the form in the instant invention, nevertheless allowed disablement of a part of their circuitry. Such a device is shown in U.S. Pat. No. 4,313,110, entitled: SMOKE ALARM HAVING TEMPORARY DISABLING FEATURES. In this application of the art, battery power is selectively applied to, or removed from, only portions of the device""s circuitry, in order to temporarily silence the alarm signal. However, power continues to be furnished to the critical areas, assuring automatic alarm (enabling) should a hazard occur. An operational mode is originally acquired when the batteries are connected, irrespective of when the device is installed. In similar fashion, U.S. Pat. No. 4,389,635, for INTERFACING ATTACHMENT FOR REMOTE MECHANICAL FIRE ALARMS discloses a switch that is part of a relay system. The switch function is magnetically induced and can be inhibited by interposition of a shield (magnetic spoiler). Tripping of the (local) fire alarm, which is an essentially mechanical activity, results in driving a lever that withdraws the shield from between the switch and a proximate magnet, thus closing the switch and activating a remote alarm circuit.
Three of the previously discussed U.S. Pats. Nos. 5,578,996, no. 5,793,295 and No. 5,444,434, particularly the figures therein, are incorporated by reference for their showing of current state-of-the-art.
The following terms shall have the indicated meanings, as may be further defined throughout this specification:
bridge(ing)xe2x80x94is synonymous with short(ing) and means an electrical connection(ing) between two or more set-apart contacts or circuit portions;
connect(able)xe2x80x94is synonymous with mate(able) and join(able), in all verb tenses, and means a union of two or more parts, portions or members in(to) the complete fashion or mode for which they are designed, such as, for example, providing electrical continuity between two or more contacts;
complementxe2x80x94is the quantity remaining after a part or portion is removed or separated from a unit or a whole, and is both definite and discrete;
contact(s)xe2x80x94is one (or more) point(s) of an electric circuit that expose a conductor;
devicexe2x80x94refers generally to something devised or constructed, but may be a design or pattern, depending on contextual usage;
drive(er)xe2x80x94refers to an article, part, etc., or force that effects a motion or state;
interleavexe2x80x94means to insert or set between a leaf, flap or tab and used herein to describe certain bayonet-type connections in apparatus;
interrupt(ion)xe2x80x94is a gap in, or the act or state of breaking or opening a circuit;
separablexe2x80x94indicates that a whole is divisible into two or more non-operative parts;
spring-biasingxe2x80x94means using any resilient article to retain/return to a position; and
unmate(d)(ing)xe2x80x94are grammatically incorrect, but will be used throughout to mean de-mate(d)(ing), because these word(s) define a single-step activity, as opposed to a two-step mate(d)(ing) activity.
All other terms of art shall have their conventional meanings or will be defined, parenthetically, with their usage.
The instant invention overcomes deficiencies in the prior art by providing to a device, a hazard detector, an on/off switching mechanism that has a physical multiple use (multiuse) capability, i.e., it can be used, repeatedly, to activate/deactivate an electrical circuit. This on/off switch, distinctive from the types commonly used in contemporary hazard devices/sensors/detectors, is made functional only upon the mating of two or more separable portions of such a device. Until the switch is activated, the device, which contains batteries and is otherwise ready to be energized, is quiescent.
According to the invention, one (major) portion of the device or detector (hereinafter, xe2x80x9csensorxe2x80x9d shall apply only to a specific element) contains essentially all the operative circuitry, power source, and sensor elements, including its protective cover. Within the circuitry an interrupt is provided consisting of a simple, single-point break embodied by two exposed, set-apart conductive points on a circuit board that contains and supports the aforesaid circuitry, power source, and sensor elements. The major portion is designed for contact and mating with its complement, the primary functions of the latter being to serve as a surface-mountable bracket and to securely retain the major portion. The mating, which is achieved by both contact and rotation (two steps) of the device""s two mentioned portions, securely engages at least two mutually-borne, interleaving tabs, or captures two or more bayonet connectors, and effects simultaneous switch activation. This facility advantageously assures that the device is not electrically activated until its two major portions are mated consistent with proper installation. Another advantage of this construction is that it nominally prevents the device from being inadvertently mounted in a deactivated state once properly installed. An unmating, by counter-rotating the major portion (one step) will immediately cause the switch to open. Thus, the switch is activated only when the major portion and its complement are mated. The installed device is deactivated merely by applying a single counter rotation motion to its protective cover.
The switch mechanism includes a shorting element and is spring-biased in a position apart from the aforesaid interrupt, and a mating of the two portions of the device urges the shorting element into contact with it. In another embodiment, the interrupt is spring-biased to extend to a prospective shorting strip location that is attained by the strip only upon full mating of the aforementioned portions. In another embodiment, the switch mechanism includes a conductive key. The device is activated only upon inserting the key fully into the device, thereby electrically connecting two or more contact springs.